Introduction
The presence of small finger-like projections (microvilli) on the inner surface of vessels characterizes the brush border. These microvilli greatly increase the surface area of the epithelium, improving product absorption and secretion. The proximal tubule of the nephron (functional unit of the kidney) is lined by a cuboidal epithelium with a microvillus brush border. In acute kidney injury (AKI), the kidneys suddenly stop working properly. It ranges from mild loss of renal function to complete renal failure. AKI usually occurs as a complication of another serious illness. As the name suggests, it is not the result of a physical blow to the kidney.
What Is Anti-Brush Border Antibody Disease?
Anti-brush border antibody (ABBA) disease is a type of nephropathy (deterioration in kidney function). It is a rare form of kidney disease that affects older patients. It is characterized by acute kidney injury (AKI) and progressive renal tubular injury associated with immunoglobulin G (IgG), also known as the antibody. IgG antibody deposits along the basement membrane of proximal tubules and circulating antibodies to the proximal tubule brush border protein LRP2 (LDL receptor-related protein 2 provides instructions for making megalin). Megalin is a protein responsible for the absorption of trace elements in the kidneys.
What Are the Causes of Anti-Brush Border Antibody Disease?
Anti-brush border antibody disease is of autoimmune origin. The immune system in autoimmune diseases attacks the body itself. Normally, the immune system protects us from bacteria and viruses. When it senses these alien invaders, it sends out an army of combat cells to attack them. Normally, the immune system can distinguish between foreign cells and its own cells. In autoimmune diseases, the immune system misidentifies parts of the body, such as joints and skin, as foreign. Proteins called autoantibodies are released that attack healthy cells.
Who Is at Risk of Anti-Brush Border Antibody Disease?
The following conditions are risk factors for anti-brush border antibody disease:
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Age - Elderly people are prone to this condition.
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Genetics - Some people are more genetically prone to this condition than other people.
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Diet - Unhealthy diet may lead to deficiencies of minerals and vitamins in the body, further leading to autoimmune conditions to occur.
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Infections - Some disorders appear to be caused or exacerbated by infections with any bacteria or virus.
What Are the Symptoms of Anti-Brush Border Antibody Disease?
The symptoms of anti-brush border antibody disease are listed below:
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Polyuria - Increased urination.
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Dysuria - Painful urination.
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Nocturia - Urination in the night.
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Urinary urgency - Difficulty retaining urine for a long time.
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Lethargy - Difficulty in carrying out daily tasks.
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High blood pressure - The blood pressure of the body becomes elevated due to malfunctioning kidneys.
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Proteinuria - The elevated presence of protein in the urine as the kidney cannot reabsorb the protein, so most of it is eliminated in the urine.
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Swelling - There is swelling of hands, feet, and legs due to fluid accumulation.
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Confusion - A person stays confused with difficulty in concentration.
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Difficulty breathing - It is harder to breathe for a person in this condition.
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Decreased appetite - Affected individuals tend to have reduced appetite and decreased hunger.
What Are the Possible Complications of Anti-Brush Border Antibody Disease?
Complications of anti-brush border antibody disease may develop suddenly due to its sudden onset and acute nature:
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Fluid retention causes swollen arms or legs, high blood pressure, or lung fluid (pulmonary edema).
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Elevated levels of potassium in the blood (hyperkalemia).
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Disorders of the heart and blood vessels that cause a stroke (cardiovascular disease).
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A decrease in the number of oxygen-carrying red blood cells (anemia).
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Leg pain, erectile dysfunction, diarrhea, and other problems related to nerve or blood vessel damage.
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Bone and mineral disorders are due to the inability to maintain a proper balance of calcium and phosphorus in the blood by the kidney.
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Pregnancy complications that pose risks to mother and fetal development.
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Irreversible damage to the kidneys (end-stage renal disease), eventually requiring dialysis or a kidney transplant for survival.
How Is Anti-Brush Border Antibody Disease Diagnosed?
Anti-brush border antibody disease is diagnosed in the ways listed below:
Routine screening tests may include the following:
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Albumin Test in Urine - This test can detect blood protein albumin in the urine. Normally, the kidneys do not filter albumin from the blood. Too much protein in the urine can indicate poor kidney function.
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Albumin and Creatinine Ratio - Creatinine is a chemical waste that healthy kidneys filter out of the blood. The albumin and creatinine ratio is a measure of the amount of albumin present in a urine sample relative to the amount of creatinine. It provides another indicator of renal function.
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Glomerular Filtration Rate (GFR) - By measuring creatinine in a blood sample, it is estimated how quickly the kidneys filter the blood (glomerular filtration rate). A low filtration rate indicates poor renal function.
Other diagnostic tests include:
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Imaging Test - The doctor may use x-rays and ultrasound to assess the structure and size of the kidneys. CT scan (computed tomography) and magnetic resonance imaging (MRI) are used to determine the state of blood circulation within the kidneys. In some cases, other image processing techniques can also be used.
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Biopsy of Kidney - The doctor may recommend a kidney biopsy to obtain a sample of kidney tissue. The sample is then seen under an electron microscope with the staining method.
How Is Anti-Brush Border Antibody Disease Treated?
Autoimmune diseases like anti-brush border antibody disease generally cannot be cured, but the condition can often be controlled in the ways listed below:
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Anti-Inflammatory Drugs - Such as Aspirin and Ibuprofen are used to reduce inflammation and pain.
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Corticosteroids - Medications such as Dexamethasone to reduce inflammation. They are sometimes used to treat acute flare-ups of symptoms.
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Pain Relievers - Medications such as Acetaminophen or Codeine.
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Immunosuppressants - Medications such as Infliximab. These drugs inhibit the activity of the immune system.
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Deficiency Treatment - Calcium and phosphorus deficiency due to renal imbalance.
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High-Dose Immunosuppression - Medications such as Adalimumab. The use of these drugs to suppress the immune system (at doses needed to treat cancer or prevent rejection of transplanted organs) has recently been tried with promising results. It appears that some of these ailments may be curable, especially if intervened early.
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Dialysis - This treatment is done to remove waste products and excess water from the blood.
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Kidney Transplant - In some cases, a kidney transplant is the best option.
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Symptom Management - Symptom management, like diarrhea, and vomiting, is done to improve the quality of life.
How to Prevent Anti-Brush Border Antibody Disease?
Anti-brush border antibody disease may not be preventable. However, it is recommended to try the following:
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Do regular exercise.
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Avoid cigarette smoking.
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Avoid toxin exposure.
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Eat healthily and limit processed foods from the diet.
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Doing yoga and deep breathing exercise.
Conclusion
Anti-brush border antibody disease is an autoimmune disease that has been discovered only recently and is found in rarity as it is underreported. It mostly affects only the elderly population. The people suffering from this condition have nephropathy and acute kidney injury, which may further lead to kidney failure. Being an autoimmune disease, this condition cannot be prevented, and only its symptoms can be managed. Permanent kidney damage may occur, leading to a need for a kidney transplant. The disease is highly aggressive, with most cases of end-stage renal disease within a year. The disease is largely unresponsive to various attempted therapeutic strategies. If people suspect anti-brush border antibody disease, they should see the doctor as soon as possible for diagnosis and treatment. Symptoms are easier to manage when they are treated promptly.
